Cerebellar long-term depression (LTD) may be reliably induced in the cultured Purkinje neuron when glutamate pulses and Purkinje neuron depolarization are applied together 6 times. When the number of these conjunctive stimuli was reduced to 2, a short-term depression (STD) lasting 20-40 min was induced in 4/12 cells. The enzyme ...

Cerebral insult is associated with a rapid increase in free fatty acids (FFA) and arachidonic acid release has been linked to the increase in eicosanoid biosynthesis. In transient focal cerebral ischemia induced by middle cerebral artery (MCA) occlusion, there is an inverse relationship between the increase in FFA and the ...

The regulation of phosphodiesterase-4 (PDE4) by various phospholipids was explored using PDE4s partially purified from U937 cells. Preincubation (5 min, 4 degrees C) of the large molecular weight PDE4 denoted "Peak 2 PDE4" with mixed phosphatidic acids (PAs) produced a 2-fold increase in its Vmax without changing its Km (approximately ...

The present study was aimed at defining the chemotactic activity of phosphatidic acid, which is rapidly produced by phagocytes in response to chemotactic agonists. Exogenously added phosphatidic acid induced human monocyte directional migration across polycarbonate filters with an efficacy (number of cell migrated) comparable to that of "classical" chemotactic factors. ...

Activation of phosphatidylinositol 3-kinase (PI 3-kinase) is necessary for stimulation of cell division and inhibition of apoptosis in several cell types. We report that a synthetic phosphonolipid, 4-(hexadecyloxy)-3-(S)-methoxybutyl phosphonic acid (PoA), as well as the naturally occurring lipids, phosphatidic acid and lyso-phosphatidic acid, are potent and specific inhibitors of PI ...

Renal medullary cells are able to accumulate glycerophosphocholine during adaptation to the high extracellular osmolality. The aim of this study was to investigate the effect of hyperosmolality on both phospholipase A2 activity and the rate of choline incorporation into glycerophosphocholine in rabbit renal medulla and Madin-Darby Canine Kidney cells. Phospholipase ...

Incubation of human thrombocytes in the presence of [3H]palmitic acid leads to incorporation of this fatty acid into the alpha subunit of Gs as described [Linder et al., Proc. Natl. Acad. Sci. USA 90 (1993) 3675-3679; Degtyarev et al., Biochemistry 32 (1993) 8057-8061] but also into the catalyst of adenylyl ...

Fibroblast contraction of stressed collagen matrices results in activation of a cAMP signal transduction pathway. This pathway involves influx of extracellular Ca2+ ions and increased production of arachidonic acid. We report that within 5 min after initiating contraction, a burst of phosphatidic acid release was detected. Phospholipase D was implicated ...

Various cell stimuli occur via activation of phospholipase A2, which hydrolyses polyunsaturated fatty acids from the sn-2 position of membrane phospholipids, resulting in the formation of polyunsaturated fatty acids and lysophospholipids. The level of lysophospholipids is determined by the balance between phospholipase A2 activity and the rate of catabolism of ...

Cellular levels of free arachidonic acid (AA) are controlled by a deacylation/reacylation cycle whereby the fatty acid is liberated by phospholipases and reincorporated by acyltransferases. We have found that the esterification of AA into membrane phospholipids is a Ca(2+)-independent process and that it is blocked up to 60-70% by a ...

Gamma- and delta-isomers of hexachlorocyclohexane caused marked decreases in the levels of radioactive phospholipids, and increases in the levels of [3H]arachidonate incorporated into free fatty acids in rat renal tubular cells. The increased radioactivity of free fatty acids arises from the decrease of [3H]arachidonate incorporated into phosphatidylinositol, but not into ...

Earlier reports have shown that, in human and rat red blood cells (RBC), ethanol modulates acylation reaction sin several membrane glycerolipid components. Little is known, however, about the kinetics and the mechanisms involved in the acylation changes. In the present study, we show that short-term in vitro exposure of intact ...

Phosphatidylcholine synthesis and degradation are tightly regulated to assure a constant amount of the phospholipid in cellular membranes. The chemotactic peptide fMLP and the phorbol ester, phorbol 12-myristate 13-acetate, are known to stimulate phosphatidylcholine degradation by phospholipase D in human neutrophils. fMLP alone triggered phosphatidylcholine breakdown into phosphatidic acid, but ...

We tested the hypothesis that serotonin activates phospholipase D (PLD) in cultured rat mesangial cells. The formation of phosphatidylethanol (PET) in ethanol was used as a measure of PLD activity. Serotonin [5-hydroxytryptamine (5-HT)] stimulated PET production, with an initial 10-fold increase in PET content within 15-30 s, followed by a ...

To compare the peroxidative susceptibilities of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in liposomes, multilamellar vesicles (MLVs) were prepared with equimolar L-alpha-dilinoleoyl PC (DLPC) and L-alpha-dilinoleoyl PE (DLPE), and with soya PC and soya PE having a uniform constituent fatty acids. The hydroperoxide formation at 37 degrees C in the presence ...

The effect of cyclophosphamide on the metabolic profile of a mammary carcinoma implanted on the foot of mouse was studied by 31P NMR spectroscopy both in vivo and in perchloric acid extracts. The ratio nucleotide triphosphate:P(i) was significantly elevated in cyclophosphamide treated tumours relative to untreated tumours after 96 h ...

The partition of free fatty acids (FFA) to egg-phosphatidylcholine (egg-PC) and egg-phosphatidylethanolamine (egg-PE) vesicles was studied. Upon the addition of FFA to the suspension of vesicles, the pH of the aqueous phase changed depending on the length and saturation of the FFA hydrocarbon chain, as well as on the vesicle ...

Several studies have shown the potential role of phosphatidic acid (PA) as a second messenger in different cell types. Thus, PA has been shown to mimic physiological agonists leading to various cellular responses, such as neurotransmitter and hormone release, cell proliferation by modulating DNA or RNA synthesis, the expression of ...

In order to assess the relationship between de novo phospholipid synthesis and remodeling by deacylation-reacylation, we have pulse-labeled glycerolipids by incubating rat hepatocytes in media containing either [U-14C]glycerol or H218O. Further incubation for up to 2 h in the absence of the labeled substrates and analysis of phosphatidylcholine (PC) and ...

Analysis of Mycoplasma penetrans membrane lipids revealed that, in addition to large amounts of unesterified cholesterol, M. penetrans incorporated exogenous phospholipids, preferentially sphingomyelin, from the growth medium. The major phospholipids synthesized de novo by M. penetrans were phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG). In vivo labeling of PG and DPG by ...

The phosphorylation of ceramide solubilized in octylglucoside/phosphatidylglycerol mixed micelles by E. coli diacylglycerol kinase was evaluated. Ceramide containing non-hydroxy fatty acids appeared to be phosphorylated quantitatively over a broad range from 25 to 2000 pmoles. If a 2-hydroxy fatty acid was present in the ceramide molecule, phosphorylation was not quantitative. ...

13C and 31P NMR spectroscopy were used to monitor interactions of lyso 1-palmitoylphosphatidylcholine (LPPC) in the interfacial region of egg phosphatidylcholine (PC) bilayers and determine the effect of LPPC on the phospholipid bilayer structure. 13C NMR spectroscopy of small amounts (0.5-10 mol%) of 13C carbonyl-enriched LPPC cosonicated with egg PC ...

N-acylphosphatidylethanolamine (NAPE) was recently shown to be synthesized in vitro in cottonseed microsomes by the direct N-acylation of phosphatidylethanolamine (PE) with unesterfied fatty acids (K.D. Chapman and T. S. Moore, 1993, Plant Physiol. 102, 761-769). Here we examine the relationship of the synthesis and turnover of NAPE in cottonseed microsomes ...

Synthetic dehydroepiandrosterone (DHEA) phosphatide 1c, (R = C15H31), was prepared by three methods. The most efficient of these involved the coupling of the commercially available DHEA 1a and commercially available phosphatidic acid 2, via mesitylene sulfonyl chloride and pyridine. Alternatively, DHEA-3-phosphate 1b was coupled with dipalmitoyl glycerol 3 in the ...

The CD52 antigen was extracted from human spleens with organic solvents and purified by immunoaffinity and reverse-phase chromatography. The latter step resolved two CD52 species, called CD52-I and CD52-II. Both species were found to contain similar N-linked oligosaccharides and glycosylphosphatidylinositol (GPI) anchor glycans. The N-linked oligosaccharides were characterized by methylation ...

The involvement of phospholipases in ischemia-evoked release of aspartate, glutamate, glycine, and GABA from the cerebral cortex was studied in a four vessel occlusion rat model of cerebral ischemia/reperfusion. In comparison with the control group, the phospholipase A2 inhibitor mepacrine significantly decreased the ischemia-evoked efflux of transmitter amino acids into ...

The rate of hydrolysis of phosphatidylcholine bilayers by soluble phospholipase A2 (PLA2) is greatly enhanced by the presence in the bilayer of a threshold mole fraction of the reaction products: fatty acid and lysophosphatidylcholine (lyso-PC). The threshold requirement of these products appears to vary as a function of vesicle and ...

This study examined the role of fatty acids on the phosphatidylcholine-specific phospholipase D (PLD) function of purified sarcolemmal (SL) membranes isolated from rat hearts. The enzyme's hydrolytic activity was determined by measuring [14C] phosphatidic acid formation from exogenous [14C] phosphatidylcholine (PtdCho) in the absence or presence of the sodium salts ...

BACKGROUND AND AIMS: Since the uveal tract becomes involved in inflammatory disorders, which are known to affect lipid metabolism, we studied normal membrane phospholipids (PLs) in order to (1) determine baseline PL profiles of the iris, ciliary body, and choroid, and (2) compare and contrast PL profiles of the uveal ...

A method was developed for the synthesis of stereo-specific sn-1,2-diacylglycerols radioactively labeled on the glycerol backbone. This method includes the acylation of L-[U-14C]glycerol 3-phosphate with fatty acid anhydrides in the presence of dimethylaminopyridine and the tetraethylammonium salt of the fatty acid used for the acylation. The phosphatidic acid obtained from ...

After dexamethasone treatment, a significant decrease in the monoenoic phosphatidylcholine 32 carbon species (palmitoyl-palmitoleylphosphatidylcholine and palmitoleyl-palmitoylphosphatidylcholine) and the phosphatidylcholine 34 carbon species (primarily palmitoyl-oleoylphosphatidylcholine) could be demonstrated both in absolute and relative terms, while the palmitic acid portion in the phosphatidylcholine fatty acids was nearly unchanged. This is in agreement ...

After betamethasone treatment, a significant diminution of the monoenoic phosphatidylcholine 32 carbon species (palmitoyl-palmitoleyl phosphatidylcholine and palmitoleyl-palmitoylphosphatidylcholine) and the phosphatidylcholine 34 carbon species (primarily palmitoyl-oleoyl-phosphatidylcholine) could be demonstrated both in absolute and relative terms, while the palmitic acid portion in the phosphatidylcholine fatty acids was nearly unchanged. This is consistent ...

OBJECTIVE: The aim was to assess whether noradrenaline and endothelin-1 can stimulate endogenous production of phosphatidic acid in adult ventricular myocytes. METHODS: After stimulation of rabbit ventricular myocytes with noradrenaline and endothelin-1, total lipids were extracted using the Bligh and Dyer procedure and separated by thin layer chromatography, and phosphatidic ...

Arachidonic acid has been implicated as a second messenger in insulin secretion on the basis of (1) mobilization of intracellular Ca2+ from the endoplasmic reticulum of islets and (2) amplification of voltage-dependent Ca2+ entry. The insulin secretagogues D-glucose and the muscarinic agonist carbachol both increase unesterified arachidonic acid accumulation in ...

The addition of exogenous oleic acid to erythrocyte membranes induces a characteristic membrane crenation and sensitises the cells to the lytic action of phospholipase A2 enzymes. Both effects are extremely sensitive to inhibition by endogenous lysophosphatidyl choline (LPC), but the strength of inhibition depends of the order in which the ...

New drugs are needed for treatment of diseases caused by African trypanosomes. One possible target for chemotherapy is the biosynthesis of the glycosyl phosphatidyl-inositol (GPI) of this parasite's variant surface glycoprotein (VSG). Unlike mammalian GPIs, the diacylglycerol moiety of the VSG anchor contains only myristate (tetradecanoate), added in unique remodeling ...

A fairly large amount of lysophosphatidylcholine (LPC) was detected in the fresh muscle of bonito Euthynnus pelamis (Linnaeus). The major fatty acid esterified in LPC were highly unsaturated fatty acids, such as docosahexaenoic and eicosapentaenoic acids, and the form was mainly composed of 1-lyso-2-acyl-sn-glycero-3-phosphocholine (1-LPC). The content of this species ...

In ram spermatozoa, treatment with the ionophore A23187 and Ca2+ led to an increase in total diacylglycerol mass and to exocytosis of the acrosomal granule. If sperm cells were prelabeled with [3H]palmitic acid, stimulation with A23187/Ca2+ resulted in the generation of [3H]diacylglycerols with a mixture of saturated and unsaturated fatty ...

We examined the incorporation of four radioactive fatty acids, 18:1n-9, 18:2n-6, 20:4n-6 and 20:5n-3, into cellular lipids of hemocytes from tobacco hornworms, Manduca sexta. Most of the radioactivity associated with 18:1n-9 was recovered from triacylglycerols (TGs), and the radioactivity associated with 18:2n-6 was heavily incorporated into phospholipids (PLs) and TGs. ...

20 min after intraportal infusion of diethyl phosphate (DEP) in rats, the mitochondrial cardiolipin (CL; 1,3-bisphosphatidyl glycerol) fraction is labelled with DEP. The obtained mixture of CL and DEP-labelled CL, which up to now has not been separated, behaves chromatographically (fractogel; HPLC: TLC), in respect to release of DEP and ...